1. Field of the Invention
This invention relates to aircraft control systems and, more particularly, to systems which present to the pilot position-controlled, generated image, cue indications on a head-up display (HUD) superimposed with visible external cues.
2. Description of the Prior Art
A head-up display (HUD) is one in which a generated image is projected onto a transparent screen in the pilot's normal line of sight so that the pilot can observe the projected image while continuing his normal observation of outside cues.
Prior HUD systems have been developed and are well known, such as a lead-computing gunsight for military aircraft and approach-to-landing path displays. The latter type of HUD designs have made use of a selectable fixed approach path depression angle and/or the instantaneous descent angle of the aircraft (velocity vector) either separately or combined in one display symbol.
One HUD system, of particular interest for commercial aircraft, is the system disclosed in my prior U.S. Pat. No. 4,104,612 entitled HEAD-UP DISPLAY COMMAND BAR GENERATOR. In that disclosure, a feedback-compensated control system makes use of the fixed depression angle combined with computed rate information to derive the HUD command signal. The pilot, by maneuvering to keep the symbol on an aimpoint (the desired touchdown zone), closes the loop of a feedback-compensated control system. The system is referred to herein as the "Compensated Control" HUD.